JP3570370B2 - Light source device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light source device for a data projector, a liquid crystal projector, and a DLP projector.
[0002]
In recent years, liquid crystal projectors and DLP projectors using digital light processing technology (DLP ^™ : Texas Instruments) have become widespread. The mainstream of these projectors is a so-called front-projection-type image monitor that projects image light from the projector onto a screen spaced from the projector. In addition, the light source is used in a bright room by increasing the luminance of the used light source and improving the light use efficiency of the liquid crystal and the DLP. In recent years, a so-called rear projection type image monitor in which a light source device and a screen are integrated has attracted attention as a home use image monitor (television).
[0003]
1A and 1B are schematic cross-sectional views of a conventional rear projection type image monitor 100. FIG. The rear projection type image monitor 100 is configured by arranging a light source device 1, an illumination system optical component 6, a back reflection mirror 3, and a screen 4 in a housing 5.
As a light source for a rear projection type image monitor, a short arc type discharge lamp such as a metal halide lamp or an ultra-high pressure mercury lamp is used. As for the trend of the rear projection type image monitor, the demand for a space-saving market demands a reduction in thickness.
[0004]
As the light source to be used, the ultra-high pressure mercury lamp is often used due to the progress of high brightness. Ultra-high pressure mercury lamps achieve higher mercury operating pressure in vertical operation than in horizontal operation, and are relatively easy to heat-resistant design of the arc tube. Vertical lighting is more desirable.
[0005]
However, in the case of FIG. 1A, the screen 4 stands vertically. In order to form a rectangular projection surface having the same upper and lower sides on the screen 4, the projection distance from the light source to the upper and lower sides of the screen 4 must be the same. If the projection distance between the upper side and the lower side is different, the projection surface becomes a trapezoid on the screen 4. Therefore, if the rear reflection mirror 3 is greatly tilted to solve the above, as a result, the depth of the rear projection type image monitor 100 increases.
Therefore, as shown in FIG. 1B, it has been considered that the irradiation light is inclined by the illumination optical system component 6 while the discharge lamp 1 is vertically lit. However, the illumination optical system component arranged in the product housing 5 is considered. 6, the degree of freedom of the layout of the rear reflection mirror 3 is reduced, and as a result, there is a problem that it is difficult to reduce the thickness of the rear projection type image monitor.
[0006]
For this purpose, as shown in FIG. 2, the lighting posture of the discharge lamp 1 is inclined from the vertical, so that the number of components of the illumination optical system component 6 including the direction limiting mirror and the prism can be reduced when the discharge lamp 1 is vertically lit. As compared with the above, the layout of the rear reflection mirror 3 becomes easy, and the thickness of the rear projection type image monitor 100 is easily reduced.
Further, the cost can be reduced by reducing the number of illumination optical system components 6.
For the above-described reasons, in order to realize a thin product design, there is a strong demand from the market to light the discharge lamp 1 at an inclination rather than vertical lighting.
[0007]
However, when the discharge lamp 1 is lighted with an inclination as described above, the problem of the continuation of the coil arc is more likely to occur than in the case of vertical lighting.
Normally, the cathode is wound around a component called a coil around the cathode core rod in consideration of lamp starting properties.However, the coil loses its main function after the discharge lamp is started, and the starting point of the arc is the operating pressure in the arc tube. As the pressure rises, it moves from the coil to the tip of the cathode core rod. The phenomenon of the above-mentioned persistence of the coil arc is that the transition of the starting point of the arc from the coil to the tip of the cathode core rod does not occur as described here, and the discharge occurs between the coil and the anode, not between the tip of the electrode originally designed as an arc gap. Is a phenomenon that keeps stabilizing. The coil is an essential component for easy starting required for the discharge lamp.
[0008]
In a DC lighting type discharge lamp, the cathode and anode are heated and sealed along the optical axis of the lamp.However, since the anode is heavier than the cathode, the tip of the anode core rod is positioned with respect to the lamp optical axis. Causes slight eccentricity. At the time of lighting, an arc flies between the eccentric tip of the anode core rod and the coil wound around the cathode. Then, depending on the position of the eccentric tip of the anode core rod, the generated coil arc may continue.
[0009]
When a coil arc occurs, the focal point of the concave reflection mirror and the arc center position deviate, making it difficult to sufficiently use the light output as a light source device and, furthermore, forming a coil by maintaining the coil arc. Tungsten evaporates and evaporates adhere to the inner wall of the quartz glass arc tube, which lowers the transmittance of the light emitting section, causing a decrease in light output on the projection surface and deformation of the light emitting section due to local temperature rise. For example, there is a problem that lamp characteristics are deteriorated.
[0010]
[Problems to be solved by the invention]
Therefore, the present invention prevents the continuous occurrence of a coil arc of a discharge lamp used in a light source device of a rear projection type image monitor, realizes a longer lamp life, and reduces the number of optical components of the rear projection type image monitor to manufacture. It is to provide a light source device with reduced cost.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that the image light irradiated upward is reflected in a horizontal direction by an inclined rear reflecting mirror, and the image light is irradiated on a vertically arranged screen. A light source device used as an irradiation light source of a rear projection type image monitor of the type described below, wherein the light source device has a concave reflecting mirror, and a sealing portion is fixed to a center hole of the concave reflecting mirror, and the sealing portion And a DC lighting discharge lamp in which a pair of cathodes and anodes are arranged opposite to each other in an arc tube continuously provided, and the optical axis of the concave reflecting mirror is directed from a vertical direction to a substantially central direction of the rear reflecting mirror. The direct-current discharge lamp is disposed so as to be inclined, the anode is disposed with the anode facing upward, and the tip of the anode is positioned on the side where the light source device is disposed obliquely above the optical axis of the lamp. Features In which a light source device for.
[0012]
According to a second aspect of the present invention, there is provided the light source device according to the first aspect, wherein an inclined arrangement angle of the light source device is not less than 5 degrees and not more than 50 degrees from a vertical axis.
[0013]
According to a third aspect of the present invention, the DC lighting discharge lamp has a lamp power of 100 W or more, and contains 0.16 mg / mm ³ or more of mercury and a rare gas or a rare gas and a halogen in the arc tube. 3. The light source device according to claim 1, wherein a tube wall load is 0.8 W / mm ² or more.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 3 is an explanatory view of a DC lighting type ultra-high pressure mercury lamp. The discharge vessel is made of quartz glass, and has an elliptical spherical light-emitting portion 8 forming a light-emitting space, and rod-shaped sealing portions 7, 7 provided so as to extend outward from both ends of the light-emitting portion 8.
[0015]
The light emitting section 8 has an anode 9 and a cathode 10 opposed to each other on the tube axis of the discharge vessel in a state where the distance between the electrodes is, for example, 2.0 mm or less. It extends and is electrically connected to the external lead 13 via the Mo foil 12 buried in the sealing portion 7 in an airtight manner.
[0016]
The anode 9 side has the same configuration, and is electrically connected to the external lead 13 via the Mo foil 12.
[0017]
Mercury is sealed in the light emitting section 8 as a light emitting substance, and a rare gas such as argon or xenon is sealed as a lighting starting gas. For example, 1.3 × 10 ⁴ Pa of rare gas is sealed. Here, the amount of enclosed mercury is 0.16 g / mm ³ or more, and this amount is such that the mercury vapor pressure during stable lighting becomes one hundred and several tens atmospheres or more. Note that halogen may be sealed to suppress blackening of the inner wall of the light emitting unit 8.
[0018]
An example of such an ultra-high pressure mercury lamp is as follows. The maximum diameter portion of the light emitting section 8 is 12.0 mm, the maximum inner diameter is 7.5 mm, the emission space length (length in the axial direction of the lamp) is 12.5 mm, the amount of enclosed mercury is 50 mg, The inner volume of the space is 260 mm ³ , the inner surface area of the light emitting space is 250 mm ² , the tube wall load is 0.8 W / mm ² , the rated power is 200 W, and the distance between the electrodes is 1.5 mm.
[0019]
This ultra-high pressure mercury lamp is attached to the concave reflecting mirror 2, and a front cover 21 made of a translucent material is attached to a front opening of the concave reflecting mirror 2 to form a light source device. The structure is shown in FIG.
The sealing portion 7 of the ultra-high pressure mercury lamp as the discharge lamp 1 projects from the top 2A (center hole) of the concave reflecting mirror 2 and is supported by the concave reflecting mirror 2 via an adhesive. Further, a base 71 with terminal screws is attached to an end of the sealing portion 7 of the discharge vessel of the ultrahigh pressure mercury lamp. A hole 22 is provided in the side surface of the concave reflecting mirror 2, a metal wire 23 for supplying power to the external lead 13 on the anode side is drawn out, and a predetermined power is supplied.
[0020]
The concave reflecting mirror 2 is made of heat-resistant hard glass, for example, borosilicate glass, and has a parabolic shape or an elliptical shape. The front opening has, for example, a substantially rectangular opening.
[0021]
The inner surface of the concave reflecting mirror 2 is made of a dielectric multilayer film in which titania (TiO ₂ ) and silica (SiO ₂ ) are alternately laminated by, for example, a vapor deposition method, and transmits only ultraviolet light and infrared light and reflects only visible light. As described above, the thickness and the number of the dielectric films are defined to form the reflection surface.
The front cover 21 is adhered to the front opening of the concave reflecting mirror 2 using an adhesive 24 such as a silicone resin adhesive.
[0022]
The central axis of the concave reflecting mirror 2 coincides with the longitudinal axis of the ultra-high pressure mercury lamp, and the emission center of the ultra-high pressure mercury lamp is located at the focal position of the concave reflecting mirror. The emitted light can be efficiently emitted in the direction of the front opening of the concave reflecting mirror.
[0023]
Lighting is performed with the lighting posture inclined at a certain angle from the vertical state in which the upper side of the anode and the lower side of the cathode are arranged. At this time, the case where the eccentric direction of the anode 9 is located on the opposite side to the direction inclined from the vertical state as shown in FIG. 5, and the case where the eccentric direction of the anode 9 and the direction inclined from the vertical state are shown in FIG. A specific description of the phenomenon in the case where they are arranged in the same direction will be described below. 5 and 6, schematic diagrams in which the vicinity of the electrodes is enlarged are shown as FIGS. 7 and 8, respectively.
7 and 8, the Mo foil is omitted for convenience.
[0024]
In general, at the time of starting the lamp, the starting point of the discharge often occurs from the coil 11 which has a smaller thermal capacity than the cathode core portion and easily emits thermionic electrons. Thereafter, the temperature inside the lamp tube rises, and the temperature of the cathode core portion increases due to heat conduction from the coil 11 and convection from the arc 14 or the flare 15 around the arc. In such a case, the starting point of the discharge shifts from the coil 11 to the tip end 10A of the cathode rod, which is the shortest discharge distance. This is a common phenomenon seen when starting a discharge lamp.
[0025]
In the lamp tube during operation, convection occurs vertically upward from the arc in the hottest part, and a flow descending along the inner wall of the lamp tube is formed.
However, when the direction of inclination and the direction of eccentricity of the anode are as shown in FIG. 5, the discharge generated in the coil is stabilized at a portion that floats in the direction opposite to the gravity due to convection. FIG. 7 is a schematic diagram in which the vicinity of the electrode is enlarged. At this time, the convection from the arc 14 or the flare 15 around the arc does not expose the tip 10A of the cathode core rod to a high-temperature atmosphere, and There is no opportunity to ascend, and the starting point of the discharge cannot move to the tip 10A of the cathode core rod, and the coil arc is maintained.
[0026]
In this case, the coil 11 having a small thermal capacity evaporates, and the evaporated tungsten adheres to the inner wall of the light emitting portion 8, so that the light transmittance is reduced at that portion, and the lamp is deteriorated or deformed by the absorption of heat. This results in impaired characteristics.
[0027]
Conversely, when the tilt direction of the light source device and the eccentric direction of the anode are arranged as shown in FIG. 6, a schematic diagram in which the vicinity of the electrodes is enlarged is shown in FIG. 8, but the discharge generated in the coil 11 floats by convection. Even when the coil core 8 is located above the coil 8, the tip 10A of the cathode core rod is exposed to the high-temperature flare 15, the temperature of the tip is increased, and the discharge is transferred to the tip 10A of the cathode core rod. As a result, the duration of the discharge in the coil 8 is eliminated, so that a discharge occurs between the tip of the cathode rod and the tip of the anode rod which are properly designed, and the designed lamp characteristics can be obtained.
[0028]
The tilted lighting range is effective when the lamp is lit at an angle from the vertical. However, when the lamp is tilted more than 50 degrees from the vertical axis, the mercury vapor pressure of the ultra-high pressure mercury lamp does not rise sufficiently, so that lamp characteristics are obtained. However, the position of the highest temperature portion of the light emitting section 8 changed depending on the inclination angle, and the devitrification of the quartz glass became remarkable.
[0029]
Further, when the inclination angle of the light source device is a small inclination angle of less than 5 degrees from the vertical axis, the problem of the coil arc continuation does not occur even in the case of assembling ignoring the relationship between the inclination lighting direction and the electrode eccentric direction as in the case of vertical lighting. It has been confirmed that the effective inclined lighting range in the present invention is not less than 5 degrees and not more than 50 degrees from the vertical axis.
[0030]
The ultra-high pressure mercury lamp used in the present invention is a DC lighting type ultra-high pressure lamp and has a lamp power of 100 W or more. If the lamp power is less than 100 W, the brightness required in the market cannot be obtained. The arc tube contains 0.16 mg / mm ³ or more of mercury, a rare gas or a rare gas and a halogen, and the tube wall load is 0.8 W / mm ² or more. In order to obtain a high-luminance point light source, it is necessary to seal 0.16 mg / mm ³ or more of mercury. In order to completely evaporate the sealed mercury, the tube wall load must be 0.8 W / mm ² or more. It is required that there be.
[0031]
【The invention's effect】
By arranging the inclined lighting direction and the electrode eccentric direction so that the tip of the anode is located on the side where the light source device is inclined from the optical axis of the lamp, the continuation of the coil arc is prevented, The same coil arc elimination as in the case of vertical lighting is performed, and a steady arc is set between the electrode tips.
[0032]
Also, by defining the inclined lighting angle, a lamp output equivalent to that during vertical lighting can be ensured, and further, it can be used under the condition that the thermal load of the arc tube does not exceed the allowable temperature range.
[0033]
Further, there is a DC lighting type ultra-high pressure lamp, which has a lamp power of 100 W or more, contains 0.16 mg / mm ³ or more of mercury, a rare gas or a rare gas and a halogen in an arc tube, and has a tube wall load of 0.8 W. / Mm ² or more, it is possible to completely evaporate the enclosed mercury and use it as a light source device of a high-brightness point light source with sufficient brightness in the application of the irradiation light source of the rear projection type image monitor. it can.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view for explaining a conventional rear projection image monitor.
FIG. 2 is a schematic sectional view for explaining a rear projection image monitor in which the light source device of the present application is arranged.
FIG. 3 is an explanatory diagram of an extra-high pressure mercury lamp.
FIG. 4 is a schematic explanatory view of a light source device.
FIG. 5 is an explanatory diagram showing a position of a discharge lamp as a comparative example in the present invention.
FIG. 6 is an explanatory diagram showing a position of a discharge lamp as an example of the present invention.
FIG. 7 is an enlarged schematic diagram illustrating a state of discharge in a comparative example of the present invention.
FIG. 8 is an enlarged schematic diagram illustrating a state of discharge as an example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Discharge lamp 2 Concave reflection mirror 2A Top part 3 Back reflection mirror 4 Screen 5 Case 6 Illumination optical system component 7 Sealing part 71 Base 8 Light emitting part 9 Anode 10 Cathode 10A Cathode core tip 11 Coil 12 Mo foil 13 External lead 14 Arc 15 Flare 21 Front cover 22 Hole 23 Metal wire 100 Rear projection type image monitor 200 Light source device

Claims (3)

The image light emitted upward is reflected in the horizontal direction by a rear reflection mirror arranged at an angle, and is used as an irradiation light source of a rear projection type image monitor in which the image light is irradiated on a vertically arranged screen. A light source device,
The light source device is a direct current lighting type in which a sealing member is fixed to a concave reflecting mirror and a central hole of the concave reflecting mirror, and a pair of cathodes and anodes are opposed to each other in an arc tube connected to the sealing portion. A discharge lamp, and the optical axis of the concave reflecting mirror is inclined from the vertical direction toward the substantially central direction of the rear reflecting mirror,
The DC lighting discharge lamp is disposed with the anode facing upward, and the tip of the anode is positioned on the side where the light source device is inclined with respect to the optical axis of the lamp. . The light source device according to claim 1, wherein an inclined arrangement angle of the light source device is not less than 5 degrees and not more than 50 degrees from a vertical axis. The DC lighting discharge lamp has a lamp power of 100 W or more, contains 0.16 mg / mm ³ or more of mercury, a rare gas or a rare gas and a halogen in the arc tube, and has a tube wall load of 0.8 W / mm. ^3. The light source device according to claim 1, wherein the number of the light sources is ^two or more.

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